1. FIELD OF THE INVENTION
This invention relates a threaded connection especially for use in a tool insertable within a subterranean well, metal-to-metal sealing integrity being maintained between threaded components of the tool itself.
2. DESCRIPTION OF THE PRIOR ART
In subterranean oil and gas well applications it is often necessary to establish metal-to-metal sealing integrity between interconnecting metal components. For example, metallic rings are often employed between mating components of flanged wellhead assemblies. The flanged components are normally bolted together without relative rotation and an annular metal ring trapped within circular grooves in the mating flanges provides sealing integrity.
Often metal-to-metal seals must also be established between threaded tubular members in a production or completion tubing string and associated components. For example, well tools, such as packers, generally comprise a plurality of tubular components joined by threaded connections. It is often necessary for these threaded connections to maintain pressure differentials thereacross. The most common method of providing pressure integrity is to use conventional elastomeric O-rings to seal the interface of the tubular members adjacent the threaded interconnection. Metal-to-metal sealing integrity is also maintained between elastically stressed mated threads on certain premium threaded connections employed for tubular members used in subterranean oil or gas wells. Premium threaded connections are shown in U.S. Pat. Nos. 3,100,656 and 3,185,502.
U.S. patent application Ser. No. 384,839, filed June 4, 1982, discloses a deformable metal-to-metal sealing ring which may be employed between two tubular components comprising a downhole tool assembly. That pending patent application, assigned to the assignee of the instant application, also discloses deformable set down rings for establishing sealing integrity between separate elements in a well tool assembly. Axial compression is applied to the tubing string to urge the set down ring into engagement with a cooperable surface on the well tool assembly. Thus metal-to-metal sealing integrity may be established without the use of premium threaded connections. The present invention comprises improved metal-to-metal seals which may be employed in a subterranean packer or similar tool used in conjunction with a tubing seal receptacle for permitting tubing movement.